Extrusion grade perlite reinforced polypropylene polymer

ABSTRACT

The invention disclosed herein is an automotive acoustic panel including a porous sound-absorption material made from a polymer and an expanded perlite. One or more silane compounds may be coupled or coated onto the expanded perlite while a coupling agent and a chemical foaming agent may additionally be added to the automotive acoustic panel.

FIELD OF THE INVENTION

The present invention generally relates to automotive paneling havingimproved noise, vibration, and harshness (NVH) properties, and morespecifically, polymer composites reinforced with perlite used to makepaneling.

BACKGROUND OF THE INVENTION

As fuel economy standards are being increased, reducing the weight of avehicle while improving aerodynamics are key priorities for theautomotive industry. To help improve aerodynamics, underbody shields arebeing added to the underside of vehicles. Although shielding can improvethe aerodynamics, these underbody shields have the negative impact ofadding weight to the vehicle. Many different approaches have been usedto reduce the weight of paneling and underbody shields on vehicles. Forexample, many manufacturers use covers and shields made from low costpolymers such as polypropylene and high density polyethylene. To helpimprove the stiffness and heat resistance of these polymers, materialfillers such as glass and talc are frequently added. These materialblends have been chosen since they are affordable and use traditionalcomponents. These materials however, lack the properties of soundattenuation and heat deflection required in vehicles.

Another approach used by manufacturers to reduce the weight whileaddressing the NVH and aerodynamic requirements required by originalequipment manufacturers (OEMs), has been to switch to shields made fromnonwoven fabrics combined with PET (polyethylene teraphthalate) orpolypropylene polymers. Although these materials are lightweight andeffective at reducing sound attenuation, they are expensive costing twoto three times as much as standard polymer shields.

Accordingly, there is a need to develop low cost materials, designs, andprocessing methods to produce products that are both lightweight andfeature improved NVH properties.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an automotive acousticpanel is provided. The automotive acoustic panel includes a poroussound-absorption material including a polymer and an expanded perlite,one or more silane compounds coated on the expanded perlite, a couplingagent, and a chemical foaming agent.

According to another aspect of the present invention, a method offorming an acoustic panel. The method includes providing an expandedperlite treated with one or more silane compounds, providing a polymerhaving a chemical foaming agent, combining the polymer and the expandedperlite to form a porous sound-absorption material, pressing the poroussound-absorption material using a double belt press to form an acousticpanel, and thermoforming the acoustic panel using a vacuum and/or amechanical mold to form the acoustic panel.

According to another aspect of the present invention, a method offorming an automotive acoustic panel is provided. The method includesproviding an expanded perlite treated with one or more silane compoundsand a coupling agent, providing a polymer having a chemical foamingagent, combining the polymer and the expanded perlite to form a poroussound-absorption material, pressing the porous sound-absorption materialusing a double belt press to form an acoustic panel, thermoforming theacoustic panel to form the automotive acoustic panel.

These and other aspects, objects, and features of the present inventionwill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a front perspective view of an automotive vehicle having anacoustic panel according to some embodiments of the present disclosure;

FIG. 2 is a bottom view of the vehicle of FIG. 1;

FIG. 3 is an expanded view of the automotive acoustic panel of FIG. 2taken from the portion III according to some embodiments of the presentdisclosure;

FIG. 4 is a cross-sectional view of the automotive acoustic panel ofFIG. 3 taken along the line IV-IV;

FIG. 5 is a partially schematic cross-sectional view of a double beltpress according to some embodiments of the present disclosure;

FIG. 6A is a partially schematic cross-sectional view of a vacuum moldheating a perlite composition according to some embodiments of thepresent disclosure;

FIG. 6B is a partially schematic cross-sectional view of a vacuum moldpositioning the heated perlite composition over the vacuum cavityaccording to some embodiments of the present disclosure;

FIG. 6C is a partially schematic cross-sectional view of a vacuum moldapplying a vacuum to the heated perlite composition according to someembodiments of the present disclosure;

FIG. 6D is a partially schematic cross-sectional view of a vacuum moldremoving the automotive acoustic panel according to some embodiments ofthe present disclosure;

FIG. 7A is a partially schematic cross-sectional view of a mechanicalmold having a heated perlite composition positioned over a mechanicalmold cavity according to some embodiments of the present disclosure;

FIG. 7B is a partially schematic cross-sectional view of a mechanicalmold with a plug forming an automotive acoustic panel according to someembodiments of the present disclosure;

FIG. 8 is a flow diagram of a method for forming an automotive acousticpanel according to some embodiments of the present disclosure; and

FIG. 9 is a table providing data for a variety of sound-absorptionmaterials according to some embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of description herein the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the device as oriented in FIG. 1. However, it isto be understood that the device may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itself,or any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

Referring to FIGS. 1-7, reference numeral 10 generally designates anautomotive acoustic panel for use in an automotive vehicle 38. Theautomotive acoustic panel 10 includes a porous sound-absorption material14 made from a polymer 18 and an expanded perlite 22. One or more silanecompounds 26 may be coupled or coated onto the expanded perlite 22 whilea coupling agent 30 and a chemical foaming agent 34 may additionally beadded to the automotive acoustic panel 10.

To enhance the impact properties and processability of the automotiveacoustic panel 10, the polymer 18 may be a polyolefin elastomer. In someembodiments, the polyolefin elastomer can be an ethylene octenecopolymer, an ethylene hexene copolymer, an ethylene propylenecopolymer, an ethylene butene copolymer, an ethylene pentene copolymer,or a combination thereof can each be used as the polymer 18. In someembodiments, the polymer 18 is the ethylene octene copolymer or ethylenebutene copolymer. In some embodiments, the polymer includespolyethylene-co-propylene, polyethylene (including HDPE, LDPE and/orLLDPE) and polypropylene, polyester, polyamide, PVC, nylons,polystyrene, polyphenylene sulfide, polyoxymethylene and polycarbonate,and combinations thereof.

The expanded perlite 22 may be a perlite derived and expanded from aperlite ore. Perlite belongs to the class of natural glasses, commonlyreferred to as volcanic glasses, which are formed by the rapid coolingof siliceous magma and lava. Perlite ore is a hydrated natural glasscontaining typically about 72-75% SiO₂, 12-14% Al₂O₃, 0.5-2% Fe₂O₃, 3-5%Na₂O, 4-5% K₂O, 0.4-1.5% CaO (by weight) and small concentrations ofMgO, TiO₂ and other metallic elements. Expanded perlite 22 and perliteore are distinguished from other natural glasses by a higher content(2-10% by weight) of chemically bonded water, the presence of avitreous, pearly luster, and characteristic concentric or arcuate onionskin-like (i.e., perlitic) fractures.

In some embodiments, the expanded perlite 22 can be milled to a finepowder having a diameter less than 0.1 mm. The non-expanded milledexpanded perlite 22 can have a very fine particle size, high blue lightbrightness, and low oil absorption, thereby permitting much greaterutility, particularly as anti-block filler products. In someembodiments, the expanded perlite 22 has a diameter of less than about0.1 mm. In other embodiments, the expanded perlite 22 has a density fromabout 0.25 g/cm³ to about 0.40 g/cm³.

The expanded perlite 22 can be coupled to or coated/treated with one ormore silane compounds 26. The silane compounds 26 used can be appliedeither as a concentrated silane or a diluted solution of silane in waterand/or alcohol. In some embodiments, the expanded perlite 22 can becoated uniformly on its surface through the use of mixing, such as witha Henschel mixer.

The silane treatment of the expanded perlite 22 can offer severaladvantages. First, adhesion can be improved between the expanded perlite22 and the polymer 18. Second, the silane compounds 26 can improve thewet-out of the expanded perlite 22 by the polymer 18. Third, the silanecompounds 26 can improve the dispersion of the expanded perlite 22 inthe polymer 18. Lastly, the silane compounds 26 can reduce the viscosityof the polymer 18/expanded perlite 22 mix.

In some embodiments, the one or more silane compounds 26 may includepolydimethyl siloxane, polymethylphenyl siloxane, di-hydroxy terminatedpolydimethyl siloxanes, dialkoxy terminated polydimethyl siloxanes,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane,3-chloropropyltrimethyoxysilane, trimethoxysilyl ethyl amine,triethoxysilyl ethyl amine, tripropoxysilyl ethyl amine, tributoxysilylethyl amine, trimethoxysilyl propyl amine, triethoxysilyl propyl amine,tripropoxysilyl propyl amine, triisopropoxysilyl propyl amine,tributoxysilyl propyl amine, trimethoxysilyl butyl amine, triethoxysilylbutyl amine, tripropoxysilyl butyl amine, tributoxysilyl butyl amine,trimethoxysilyl pentyl amine, triethoxysilyl pentyl amine,tripropoxysilyl pentyl amine, tributoxysilyl pentyl amine,trimethoxysilyl hexyl amine, triethoxysilyl hexyl amine, tripropoxysilylhexyl amine, tributoxysilyl hexyl amine, trimethoxysilyl heptyl amine,triethoxysilyl heptyl amine, tripropoxysilyl heptyl amine,tributoxysilyl heptyl amine, trimethoxysilyl octyl amine, triethoxysilyloctyl amine, tripropoxysilyl octyl amine, tributoxysilyl octyl amine, orcombinations thereof.

The coupling agent 30 can help improve the mixing and/or adhesion of thepolymer 18 with expanded perlite 22 to form the porous sound-absorptionmaterial 14. In some embodiments, an example coupling agent may includemaleic anhydride grafted polypropylene (MAPP) (tradename EastmanG-3003). The MAPP is coupled to enhance the bond between the expandedperlite 22 (with or without silane coating) and the polymer 18. Theamount of the coupling agent 30 that can be added or coupled to thepolymer 18 can be varied from 0 to about 5.0 wt % of the automotiveacoustic panel 10. In some embodiments, the coupling agent 30 is about0.1% to about 5.0% by weight of the automotive acoustic panel. In someembodiments, the amount of the coupling agent 30 can be about 1 wt % andwas chosen since minimal property improvement is achieved at greaterloadings. In some embodiments, the coupling agent 30 includes maleicanhydride grafted polypropylene.

To further reduce the density of the automotive acoustic panel 10, thechemical foaming agent 34 may be added to the polymer 18 and expandedperlite 22 mixture. The added chemical foaming agent 34 may furtherreduce the density when the chemical foaming agent 34 decomposesproducing either carbon dioxide and/or nitrogen gasses. The byproductcarbon dioxide and/or nitrogen gasses liberated from the decompositionof the chemical foaming agent 34 result in a sheet with a fine, uniformcellular structure that can help capture noise thus improving the noiseattenuation of the automotive acoustic panel 10. The chemical foamingagent 34 can significantly reduce the density of the automotive acousticpanel 10 when a 0% to 20% by weight chemical foaming agent 34 is used.In some embodiments, the chemical foaming agent 34 has a weight percentno more than 8 wt %.

In some embodiments, the chemical foaming agent 34 includes sodiumcarbonate, sodium hydrogen carbonate, magnesium carbonate, magnesiumhydrogen carbonate, calcium carbonate, calcium hydrogen carbonate,aluminum carbonate, aluminum hydrogen carbonate, iron carbonate, ironhydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate,ammonium carbamate and mixtures thereof. In some embodiments, thechemical foaming agent 34 is about 0.1% to about 20% by weight of theautomotive acoustic panel.

Other optional additives that may be used with the poroussound-absorption material 14 include materials that can enhance color,retard fire, or improve the UV stability of the resultant automotiveacoustic panel 10. One potential additive includes coloringconcentrates. Since most automotive acoustic panels 10 will be black,carbon black may be added to the composition. Other colors may be addedas desired based on the application and final use. Color concentratesthat are compatible with polyethylene, polypropylene, or the polymer 18will be used. Depending on the required level of flame resistancerequired for the automotive acoustic panel 10, a flame retardant can beadded to the porous sound-absorption material 14. In some embodiments,the flame retardant can be a brominated flame retardant or a chlorinatedretardant. In other embodiments, non-halogenated materials can also beused as flame retardant such as phosphorus or metal oxide basedcompounds depending on the application. If UV stability is required forthe automotive acoustic panel 10, a UV light stabilizer can be used asan additive where the UV light stabilizer can be a hindered amine,benzophenone, benzotriazole, or combinations thereof that can be addedto the porous sound-absorption material 14. In some embodiments, theautomotive acoustic panel 10 further includes a coloring agent, a flameretardants, a UV light stabilizer, or combinations thereof.

Referring to FIG. 1, a wheeled automotive vehicle 38 having one or moreautomotive acoustic panels 10 (not shown) coupled to the bottom of thevehicle 38 is provided. The vehicle 38 is shown as a car although thetype of vehicle 38 is not meant to be limiting and the vehicle 38 couldadditionally be, for example, a minivan, truck, commercial vehicle, orany other wheeled motorized vehicle. The vehicle 38 additionally has apassenger compartment 40 for passengers.

Referring now to FIG. 2, the bottom of the vehicle 38 is shown havingone or more automotive acoustic panels 10. The automotive acoustic panel10 can be positioned across the bottom of the vehicle 38 to minimizeexposed area of the vehicle 38 to the outside environment and maximizethe NVH reduction of sound going into the passenger compartment.

Referring now to FIG. 3, an expanded view of the automotive acousticpanel 10 of FIG. 2 taken from the portion III is provided. The surfaceof the automotive acoustic panel 10 shows the polymer 18 and expandedperlite 22 mixed together to form the porous sound-absorption material14.

Referring now to FIG. 4, a cross-sectional view of the automotiveacoustic panel 10 represented in FIG. 3 is shown taken along the lineIV-IV. The cross-sectional view of the automotive acoustic panel 10shows the dispersion of the expanded perlite 22 disposed in the polymer18 across the porous sound-absorption material 14.

Referring now to FIG. 5, a double belt press 42 is shown for pressingand/or laminating the polymer 18 and the expanded perlite 22 into aperlite composite sheet 70. The double belt press 42 includes twothermally reinforced stable TEFLON® and glass coated belts that arearranged horizontally one on top of the other. After thoroughly mixingthe polymer 18 pellets and expanded perlite 22 to form a perlite polymermixture 46, the materials are evenly spread in a single layer across theentire width of an extended lower belt 54 by a scattering unit or anaddition member 50 that continuously mixes and disperses a single layerof the polymer 18 and expanded perlite 22. The back sides of the lower54 and upper belts are in contact with heating and cooling platens.While the lower platens are mounted rigidly, the upper platens are ableto move in a vertical direction together with the entire upper belt inorder to create a gap according to the required thickness of the perlitecomposite sheet 70. One or more pairs of calibrating nip rolls 62 aremounted after a heating zone 58 and are used to tune the thickness ofthe molded perlite composite sheet 70. The perlite composite sheet 70 isnext conveyed to an annealing zone 66 where the material is cooled to adesired temperature. The perlite composite sheet 70 can then be cut to adesired length of spooled onto a roll. The resulting double belt press42 process is competitive with other sheet extrusion methods. Themaximum pressure that is applied to the perlite composite sheet 70 andthis double belt press 42 process is less than 200 psi.

Referring now to FIGS. 6A-6D, a vacuum thermoform 74 is shownfabricating the automotive acoustic panel 10. As shown in FIG. 6A, thevacuum thermoform 74 includes a radiant heater 78 and a clamping member82 to hold and position the perlite composite sheet 70. The clampingmember 82 can be lowered with the perlite composite sheet 70 into areceiving member 86 of a vacuum mold 90 where the heated perlitecomposite sheet 70 is sucked or drawn down into a vacuum mold cavity 94where the vacuum is applied through one or more vacuum holes 98 and avacuum draw 102. As shown in FIG. 6B, the vacuum is applied to theheated perlite composite sheet 70 and the softened perlite compositesheet 70 is drawn down into the vacuum mold cavity 94 as shown in FIG.6C. As shown in FIG. 6D, once cooled, the formed automotive acousticpanel 10 is removed from the vacuum mold cavity 94 of the vacuum mold 90and the automotive acoustic panel 10 is removed from the clamping member82.

Referring now to FIG. 7A-7B, a mechanical thermoform 106 is shownfabricating the automotive acoustic panel 10. As shown in FIG. 7A, themechanical thermoform 106 includes a clamping member 110 that positionsand couples to the perlite composite sheet 70 and where the clampingmember 110 can then be positioned on a receiving member 114. As shown inFIG. 7B, the mechanical thermoform 106 then uses a plug 118 tomechanically deform the heated perlite composite sheet 70 into themechanical mold cavity 122 of the mechanical mold 126. As the heatedperlite composite sheet 70 is formed into the mechanical mold cavity122, air is removed from the mechanical mold cavity 122 via vent holes130 and a vent port 134. After the perlite composite sheet 70 is moldedinto the desired shape of the mechanical mold 126, the perlite compositesheet 70 is cooled and the desired automotive acoustic panel 10 isremoved from the mechanical thermoform 106.

Referring now to FIGS. 1-8, the method 300 of forming the automotiveacoustic panel 10 includes providing the expanded perlite 22 treatedwith one or more silane compounds 26 (step 204) and providing thepolymer 18 having the chemical foaming agent (step 208). The method alsoincludes combining the polymer 18 and the expanded perlite 22 to formthe porous sound-absorption material 14 (step 212). The method furtherincludes pressing the porous sound-absorption material 14 using thedouble belt press 42 to form the perlite composite sheet 70 (step 216).Lastly, the method further includes thermoforming the perlite compositesheet 70 to form the automotive acoustic panel 10 (step 220).

Referring now to FIG. 9, the comparative example base formula includesthe composition used for a 20 wt % talc filled polypropylene sample andits corresponding material properties defining the elongation at yield,tensile modulus, flex modulus, and Izod impact values. Additionallyincluded in FIG. 9 is a disclosed: Targeted Formula (1); AlternateHigher Stiffness Formula (2); Alternate Low Density Formula (3); and asecond Alternate Low Density Formula (4). The elongation at yield,tensile modulus, flex modulus, and Izod impact values are additionallyprovided for the inventive Targeted Formula (1); Alternate HigherStiffness Formula (2); Alternate Low Density Formula (3); and secondAlternate Low Density Formula (4).

It is understood that the descriptions outlining and teaching theautomotive acoustic panel 10 previously discussed, which can be used inany combination, apply equally well to the second embodiment, whereapplicable, further disclosing a method of forming the automotiveacoustic panel 10.

It will be understood by one having ordinary skill in the art thatconstruction of the described device and other components may not belimited to any specific material. Other exemplary embodiments of thedevice disclosed herein may be formed from a wide variety of materials,unless described otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms, couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature or may be removableor releasable in nature unless otherwise stated.

It is also important to note that the construction and arrangement ofthe elements of the device as shown in the exemplary embodiments isillustrative only. Although only a few embodiments of the presentinnovations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example,elements shown as integrally formed may be constructed of multiple partsor elements shown as multiple parts may be integrally formed, theoperation of the interfaces may be reversed or otherwise varied, thelength or width of the structures and/or members or connector or otherelements of the system may be varied, the nature or number of adjustmentpositions provided between the elements may be varied. It should benoted that the elements and/or assemblies of the system may beconstructed from any of a wide variety of materials that providesufficient strength or durability, in any of a wide variety of colors,textures, and combinations. Accordingly, all such modifications areintended to be included within the scope of the present innovations.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions, and arrangement of the desired andother exemplary embodiments without departing from the spirit of thepresent innovations.

It will be understood that any described processes or steps withindescribed processes may be combined with other disclosed processes orsteps to form structures within the scope of the present device. Theexemplary structures and processes disclosed herein are for illustrativepurposes and are not to be construed as limiting.

It is also to be understood that variations and modifications can bemade on the aforementioned structure without departing from the conceptsof the present invention, and further it is to be understood that suchconcepts are intended to be covered by the following claims unless theseclaims by their language expressly state otherwise.

The above description is considered that of the illustrated embodimentsonly. Modifications of the device will occur to those skilled in the artand to those who make or use the device. Therefore, it is understoodthat the embodiments shown in the drawings and described above is merelyfor illustrative purposes and not intended to limit the scope of thedevice, which is defined by the following claims as interpretedaccording to the principles of patent law, including the Doctrine ofEquivalents.

LISTING OF NON-LIMITING EMBODIMENTS

Embodiment A is an automotive acoustic panel comprising: a poroussound-absorption material comprising a polymer and an expanded perlite;one or more silane compounds coated on the expanded perlite; a couplingagent; and a chemical foaming agent.

The automotive acoustic panel of Embodiment A wherein the polymercomprises polyethylene-co-propylene, polyethylene, polypropylene,polyester, polyamide, PVC, nylons, polystyrene, polyphenylene sulfide,polyoxymethylene and polycarbonate, and combinations thereof.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the expanded perlite has a densityfrom about 0.25 g/cm³ to about 0.40 g/cm³.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the expanded perlite has a diameterof less than about 0.1 mm.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the one or more silane compoundscomprise polydimethyl siloxane, polymethylphenyl siloxane, di-hydroxyterminated polydimethyl siloxanes, dialkoxy terminated polydimethylsiloxanes, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane,3-chloropropyltrimethyoxysilane, trimethoxysilyl ethyl amine,triethoxysilyl ethyl amine, tripropoxysilyl ethyl amine, tributoxysilylethyl amine, trimethoxysilyl propyl amine, triethoxysilyl propyl amine,tripropoxysilyl propyl amine, triisopropoxysilyl propyl amine,tributoxysilyl propyl amine, trimethoxysilyl butyl amine, triethoxysilylbutyl amine, tripropoxysilyl butyl amine, tributoxysilyl butyl amine,trimethoxysilyl pentyl amine, triethoxysilyl pentyl amine,tripropoxysilyl pentyl amine, tributoxysilyl pentyl amine,trimethoxysilyl hexyl amine, triethoxysilyl hexyl amine, tripropoxysilylhexyl amine, tributoxysilyl hexyl amine, trimethoxysilyl heptyl amine,triethoxysilyl heptyl amine, tripropoxysilyl heptyl amine,tributoxysilyl heptyl amine, trimethoxysilyl octyl amine, triethoxysilyloctyl amine, tripropoxysilyl octyl amine, tributoxysilyl octyl amine, orcombinations thereof.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the coupling agent comprises maleicanhydride grafted polypropylene.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the coupling agent is about 0.1% toabout 5.0% by weight of the automotive acoustic panel.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the chemical foaming agent comprisessodium carbonate, sodium hydrogen carbonate, magnesium carbonate,magnesium hydrogen carbonate, calcium carbonate, calcium hydrogencarbonate, aluminum carbonate, aluminum hydrogen carbonate, ironcarbonate, iron hydrogen carbonate, ammonium carbonate, ammoniumhydrogen carbonate, ammonium carbamate, or combinations thereof.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features wherein the chemical foaming agent is about0.1% to about 20% by weight of the automotive acoustic panel.

The automotive acoustic panel of Embodiment A or Embodiment A with anyof the intervening features further comprising a coloring agent, a flameretardant, a UV light stabilizer, or combinations thereof.

Embodiment B is a method of forming an acoustic panel, the methodcomprising: providing an expanded perlite treated with one or moresilane compounds; providing a polymer having a chemical foaming agent;combining the polymer and the expanded perlite to form a poroussound-absorption material; pressing the porous sound-absorption materialusing a double belt press to form a perlite composite sheet; andthermoforming the perlite composite sheet using a vacuum and/or amechanical mold to form the acoustic panel.

The method of Embodiment B further comprising: contacting a couplingagent to the expanded perlite treated with the one or more silanecompounds.

The method of Embodiment B or Embodiment B with any of the interveningfeatures wherein the polymer comprises polyethylene-co-propylene,polyethylene, polypropylene, polyester, polyamide, PVC, nylons,polystyrene, polyphenylene sulfide, polyoxymethylene and polycarbonate,and combinations thereof.

The method of Embodiment B or Embodiment B with any of the interveningfeatures wherein the expanded perlite has a density from about 0.25g/cm³ to about 0.40 g/cm³ and the expanded perlite has a diameter ofless than about 0.1 mm.

The method of Embodiment B or Embodiment B with any of the interveningfeatures wherein the one or more silane compounds comprise polydimethylsiloxane, polymethylphenyl siloxane, di-hydroxy terminated polydimethylsiloxanes, dialkoxy terminated polydimethyl siloxanes,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane,3-chloropropyltrimethyoxysilane, trimethoxysilyl ethyl amine,triethoxysilyl ethyl amine, tripropoxysilyl ethyl amine, tributoxysilylethyl amine, trimethoxysilyl propyl amine, triethoxysilyl propyl amine,tripropoxysilyl propyl amine, triisopropoxysilyl propyl amine,tributoxysilyl propyl amine, trimethoxysilyl butyl amine, triethoxysilylbutyl amine, tripropoxysilyl butyl amine, tributoxysilyl butyl amine,trimethoxysilyl pentyl amine, triethoxysilyl pentyl amine,tripropoxysilyl pentyl amine, tributoxysilyl pentyl amine,trimethoxysilyl hexyl amine, triethoxysilyl hexyl amine, tripropoxysilylhexyl amine, tributoxysilyl hexyl amine, trimethoxysilyl heptyl amine,triethoxysilyl heptyl amine, tripropoxysilyl heptyl amine,tributoxysilyl heptyl amine, trimethoxysilyl octyl amine, triethoxysilyloctyl amine, tripropoxysilyl octyl amine, tributoxysilyl octyl amine,and mixtures thereof.

The method of Embodiment B or Embodiment B with any of the interveningfeatures wherein the coupling agent comprises maleic anhydride graftedpolypropylene and is about 0.1% to about 5.0% by weight of theautomotive acoustic panel.

The method of Embodiment B or Embodiment B with any of the interveningfeatures further comprising: providing a coloring agent, a flameretardant, a UV light stabilizer, or combinations thereof to the poroussound-absorption material.

Embodiment C is a method of forming an automotive acoustic panel, themethod comprising: providing an expanded perlite treated with one ormore silane compounds and a coupling agent; providing a polymer having achemical foaming agent; combining the polymer and the expanded perliteto form a porous sound-absorption material; pressing the poroussound-absorption material using a double belt press to form a perlitecomposite sheet; and thermoforming the perlite composite sheet to formthe automotive acoustic panel.

The method of Embodiment C wherein the thermoforming uses a vacuum moldand/or a mechanical mold.

The method of Embodiment C or Embodiment C with any of the interveningfeatures wherein the coupling agent comprises maleic anhydride graftedpolypropylene and the coupling agent is about 0.1% to about 5.0% byweight of the automotive acoustic panel.

What is claimed is:
 1. An automotive acoustic panel comprising: a poroussound-absorption material comprising a base polymer and an expandedperlite, wherein the base polymer comprises at least 80% by weight ofthe automotive acoustic panel and is selected frompolyethylene-co-propylene, polyethylene, polypropylene, polyester,polyamide, PVC, nylons, polystyrene, polyphenylene sulfide,polyoxymethylene, polycarbonate, or combinations thereof; one or moresilane compounds coated on the expanded perlite; a coupling agent,wherein the coupling agent is about 1.0% to about 5.0% by weight of theautomotive acoustic panel; and a chemical foaming agent.
 2. Theautomotive acoustic panel of claim 1, wherein the expanded perlite has adensity from about 0.25 g/cm³ to about 0.40 g/cm³.
 3. The automotiveacoustic panel of claim 1, wherein the expanded perlite has a diameterof less than about 0.1 mm.
 4. The automotive acoustic panel of claim 1,wherein the one or more silane compounds is selected from polydimethylsiloxane, polymethylphenyl siloxane, di-hydroxy terminated polydimethylsiloxanes, dialkoxy terminated polydimethyl siloxanes,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane,3-chloropropyltrimethyoxysilane, trimethoxysilyl ethyl amine,triethoxysilyl ethyl amine, tripropoxysilyl ethyl amine, tributoxysilylethyl amine, trimethoxysilyl propyl amine, triethoxysilyl propyl amine,tripropoxysilyl propyl amine, triisopropoxysilyl propyl amine,tributoxysilyl propyl amine, trimethoxysilyl butyl amine, triethoxysilylbutyl amine, tripropoxysilyl butyl amine, tributoxysilyl butyl amine,trimethoxysilyl pentyl amine, triethoxysilyl pentyl amine,tripropoxysilyl pentyl amine, tributoxysilyl pentyl amine,trimethoxysilyl hexyl amine, triethoxysilyl hexyl amine, tripropoxysilylhexyl amine, tributoxysilyl hexyl amine, trimethoxysilyl heptyl amine,triethoxysilyl heptyl amine, tripropoxysilyl heptyl amine,tributoxysilyl heptyl amine, trimethoxysilyl octyl amine, triethoxysilyloctyl amine, tripropoxysilyl octyl amine, tributoxysilyl octyl amine, orcombinations thereof.
 5. The automotive acoustic panel of claim 1,wherein the coupling agent comprises maleic anhydride graftedpolypropylene.
 6. The automotive acoustic panel of claim 1, wherein thechemical foaming agent comprises sodium carbonate, sodium hydrogencarbonate, magnesium carbonate, magnesium hydrogen carbonate, calciumcarbonate, calcium hydrogen carbonate, aluminum carbonate, aluminumhydrogen carbonate, iron carbonate, iron hydrogen carbonate, ammoniumcarbonate, ammonium hydrogen carbonate, ammonium carbamate, orcombinations thereof.
 7. The automotive acoustic panel of claim 6,wherein the chemical foaming agent is about 0.1% to about 20% by weightof the automotive acoustic panel.
 8. The automotive acoustic panel ofclaim 1, further comprising a coloring agent, a flame retardant, a UVlight stabilizer, or combinations thereof.